Non-Covalent Assembly of Proton Donors and p-Benzoquinone Anions for Co-Electrocatalytic Reduction of Dioxygen

Proton Donors ◽

High Concentrations ◽

Electron Reduction ◽

With weak acids (AH) at high concentrations, potential inversion can occur due to favorable hydrogen-bonding interactions with the intermediate monoanion [BQ(AH)m]•–. The solvation shell created by these interactions can mediate a proton-coupled electron transfer at more positive potentials, resulting in an overall two electron reduction ([BQ(AH)m]•– + nAH + e– ⇌ [HBQ(AH)(m+n)-1(A)]2–). Here we show that the resultant hydrogen-bonded [HBQ]– adduct mediates the transfer of electrons and the proton donor 2,2,2-trifluoroethanol (TFEOH) to a Mn-based complex during the electrocatalytic reduction of dioxygen (O2). The Mn electrocatalyst is selective for H2O2 with only TFEOH and O2 present, however, with BQ present under otherwise analogous conditions, an electrogenerated [HBQ(AH)4(A)]2– adduct (where AH = TFEOH) alters product selectivity to 96(±0.5)% H2O in a co-electrocatalytic fashion. These results suggest that hydrogen-bonded [HBQ]– dianions can function in an analogous co-electrocatalytic manner to H2Q.

Proton transfer in bacterial nitric oxide reductase

Biochemical Society Transactions ◽

10.1042/bst0340188 ◽

2006 ◽

Vol 34 (1) ◽

pp. 188-190 ◽

Cited By ~ 13

Author(s):

U. Flock ◽

J. Reimann ◽

P. Ädelroth

Keyword(s):

Nitric Oxide ◽

Proton Transfer ◽

Structural Model ◽

No Reduction ◽

Paracoccus Denitrificans ◽

Proton Donor ◽

Nitric Oxide Reductase ◽

Reduction Of No ◽

Electron Reduction

The NOR (nitric oxide reductase) from Paracoccus denitrificans catalyses the two-electron reduction of NO to N2O (2NO+2H++2e−→N2O+H2O). The NOR is a divergent member of the superfamily of haem-copper oxidases, oxygen-reducing enzymes which couple the reduction of oxygen with translocation of protons across the membrane. In contrast, reduction of NO catalysed by NOR is non-electrogenic which, since electrons are supplied from the periplasmic side of the membrane, implies that the protons needed for NO reduction are also taken from the periplasm. Thus NOR must contain a proton-transfer pathway leading from the periplasmic side of the membrane into the catalytic site. The proton pathway has not been identified, and the mechanism and timing of proton transfer during NO reduction is unknown. To address these questions, we have studied the reaction between NOR and the chemically less reactive oxidant O2 [Flock, Watmough and Ädelroth (2005) Biochemistry 44, 10711–10719]. When fully reduced NOR reacts with O2, proton-coupled electron transfer occurs in a reaction that is rate-limited by internal proton transfer from a group with a pKa of 6.6. This group is presumably an amino acid residue close to the active site that acts as a proton donor also during NO reduction. The results are discussed in the framework of a structural model that identifies possible candidates for the proton donor as well as for the proton-transfer pathway.

Theoretical study of hydrogen bonding interactions in substituted nitroxide radicals

New Journal of Chemistry ◽

10.1039/d0nj05362g ◽

2021 ◽

Author(s):

Thufail M. Ismail ◽

Neetha Mohan ◽

P. K. Sajith

Keyword(s):

Hydrogen Bonding ◽

Interaction Energy ◽

Electrostatic Potential ◽

Molecular Electrostatic Potential ◽

Theoretical Study ◽

Nitroxide Radicals ◽

Bonded Complexes ◽

Interaction energy (Eint) of hydrogen bonded complexes of nitroxide radicals can be assessed in terms of the deepest minimum of molecular electrostatic potential (Vmin).

Influence of intermolecular hydrogen bonding interactions on the electrocatalytic reduction of CO2 to CO by 6,6'‐amine substituted rhenium bipyridine complexes

ChemElectroChem ◽

10.1002/celc.202100306 ◽

2021 ◽

Author(s):

Ashley N. Hellman ◽

Ralf Haiges ◽

Smaranda C Marinescu

Keyword(s):

Hydrogen Bonding ◽

Intermolecular Hydrogen Bonding ◽

Reduction Of Co2 ◽

Electrocatalytic Reduction Of Co2

Probing Hydrogen-Bonding Interactions within Phenol-Benzimidazole Proton-Coupled Electron Transfer Model Complexes with Cryogenic Ion Vibrational Spectroscopy

The Journal of Physical Chemistry A ◽

10.1021/acs.jpca.1c05879 ◽

2021 ◽

Author(s):

Liangyi Chen ◽

Joseph A. Fournier

Keyword(s):

Electron Transfer ◽

Hydrogen Bonding ◽

Vibrational Spectroscopy ◽

Transfer Model ◽

Model Complexes ◽

Hydrogen Bonding Interactions

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

Spectroscopic investigations of hydrogen bonding interactions in the gas phase. II. The determination of the geometry and potential constants of the hydrogen-bonded heterodimer CH 3 CN • • • HF from its microwave rotational spectrum

10.1098/rspa.1980.0031 ◽

1980 ◽

Vol 370 (1741) ◽

pp. 239-255 ◽

Cited By ~ 42

Keyword(s):

Hydrogen Bonding ◽

Gas Phase ◽

Spectroscopic Constants ◽

Rotational Spectrum ◽

Isotopic Species ◽

Microwave Rotational Spectrum ◽

Vibration Rotation ◽

The microwave rotational spectrum of the hydrogen-bonded heterodimer CH 3 CN • • • HF has been identified and shown to be characteristic of a symmetric top. A detailed analysis of several rotational transitions for a variety of isotopic species gives the spectroscopic constants summarized in the following table: Rotational constants/MHz, vibration-rotation constants/MHz and vibrational separations/cm -1 of CH 3 CN • • • HF

Proton-coupled electron transfer in the electrocatalysis of CO2 reduction: prediction of sequential vs. concerted pathways using DFT

Chemical Science ◽

10.1039/c6sc02984a ◽

2017 ◽

Vol 8 (1) ◽

pp. 458-465 ◽

Cited By ~ 72

Author(s):

Adrien J. Göttle ◽

Marc T. M. Koper

Keyword(s):

Electron Transfer ◽

Co2 Reduction ◽

Cobalt Porphyrin ◽

Detailed Picture

We provide a complete and computationally detailed picture of the mechanism of the initial stages of the electrocatalytic reduction of CO2 in water catalysed by cobalt porphyrin complexes.

Electrocatalytic reduction of oxygen with phenanthroline-strapped porphyrins

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424607000278 ◽

2007 ◽

Vol 11 (04) ◽

pp. 212-221 ◽

Cited By ~ 9

Author(s):

Frédéric Melin ◽

Corinne Boudon ◽

Mamadou Lo ◽

Kurt J. Schenk ◽

Michel Bonin ◽

...

Keyword(s):

Pyrolytic Graphite ◽

Iron Complex ◽

X Ray Diffraction ◽

X Ray ◽

Alkyl Chains ◽

Saturated Water ◽

Electron Reduction ◽

Disk Electrodes ◽

Parent Ligand

The electrochemical behavior of three cytochrome c oxidase models has been investigated. All the models are derived from a phenanthroline-strapped, porphyrin framework that binds zinc(II) or iron(III) chloride in the porphyrin subunit, and copper(I) in the phenanthroline site. The iron complex and the bimetallic zinc(II) copper(I) complex of the parent ligand have been characterized by X-ray diffraction. One model consists of the parent structure on which C 12 alkyl chains have been added. This soluble model achieves electrochemical 2-electron reduction of oxygen in organic solvents without the addition of an exogenous axial base, and in the presence of an organic or inorganic source of protons. The two other models comprise the parent phenanthroline-strapped porphyrin framework, on which two pendant imidazoles have been incorporated. These models adsorbed on ring-disk electrodes with an edge-oriented, pyrolytic graphite (EOPG) disk and a platinum ring, efficiently catalyze the 4-electron reduction of oxygen in dioxygen saturated water at neutral pH.

Hydrogen bonding interactions in single component molecular conductors based on metal (Ni, Au) bis(dithiolene) complexes

Dalton Transactions ◽

10.1039/d0dt00960a ◽

2020 ◽

Vol 49 (18) ◽

pp. 6056-6064 ◽

Cited By ~ 1

Author(s):

Hadi Hachem ◽

Nathalie Bellec ◽

Marc Fourmigué ◽

Dominique Lorcy

Keyword(s):

Hydrogen Bonding ◽

Closed Shell ◽

Single Component ◽

Molecular Conductors ◽

Nickel (closed-shell) or gold (radical) bis(dithiolene) neutral complexes, functionalized with hydroxyethyl and thiazole moieties, afford hydrogen-bonded single component conductors.